Scientists have succeeded in transforming skin cells from two sisters with motor neurone disease into the same kind of nerve cells being destroyed by their illness, raising the possibility that the new cells can be transplanted back into them to offset the degenerative condition.
In a major breakthrough, the skin cells of the two women, aged 82 and 89, were turned into mature nerve cells. The achievement promises to revolutionise the understanding and treatment of a range of incurable illnesses.
The skin cells were genetically altered by a laboratory technique that "reprogrammed" them back to their original embryonic state, before being grown into the specialised motor neurons that carry signals from brain to muscles.
Scientists hope that the creation of adult nerve cells from the skin of patients with motor neurone disease – which cripples muscles – will result in a better understanding of how things go wrong, as well as leading to a new approach to testing drugs and therapies that could lead to better treatments, or possibly a cure.
"No one has ever managed to isolate these neurons from a patient and grow them in a dish," said Professor Kevin Eggan, of Harvard University in Cambridge, Massachusetts, who led the study, published in the journal Science. "Now we can make limitless supplies of the cells that die in this awful disease. This will allow us to study these neurons in a lab dish and figure out what's happening."
The scientists had intended to create stem cells from motor neurone patients using the more morally contentious technique of embryo cloning pioneered in the creation of Dolly the sheep. But a shortage of human eggs led them to try an approach developed in Japan which involves altering four key genes of skin cells. Because this neither creates nor destroys a human embryo, it is considered more ethically acceptable.
As a result, the scientists managed to create induced pluripotent stem (iPS) cells, as the cells are called, from two patients, one 89 and the other 91, with mild forms of a type of motor neurone disease known as amyotrophic lateral sclerosis (ALS).
"Up until now, it's been impossible to get access to the neurons affected by ALS and, although everyone was excited by the potential of the new technology, it was uncertain that we would be able to obtain them from patient's skin cells," said Professor Chris Henderson, of Columbia University Medical Centre in New York, said:
"Our study now shows that we can generate hundreds of millions of motor neurons that are genetically identical to a patient's own neurons. "This will be an immense help as we try to uncover the mechanisms behind the disease and screen for drugs that can prolong life."